1.4 (2012-12-18)
================
Docs
----
- Fix functional tests in the ZODB tutorial
1.4b3 (2012-12-10)
==================
- Packaging release only, no code changes. 1.4b2 was a brownbag release due to
missing directories in the tarball.
1.4b2 (2012-12-10)
==================
Docs
----
- Scaffolding is now PEP-8 compliant (at least for a brief shining moment).
- Tutorial improvements.
Backwards Incompatibilities
---------------------------
- Modified the ``_depth`` argument to ``pyramid.view.view_config`` to accept
a value relative to the invocation of ``view_config`` itself. Thus, when it
was previously expecting a value of ``1`` or greater, to reflect that
the caller of ``view_config`` is 1 stack frame away from ``venusian.attach``,
this implementation detail is now hidden.
- Modified the ``_backframes`` argument to ``pyramid.util.action_method`` in a
similar way to the changes described to ``_depth`` above. This argument
remains undocumented, but might be used in the wild by some insane person.
1.4b1 (2012-11-21)
==================
Features
--------
- Small microspeed enhancement which anticipates that a
``pyramid.response.Response`` object is likely to be returned from a view.
Some code is shortcut if the class of the object returned by a view is this
class. A similar microoptimization was done to
``pyramid.request.Request.is_response``.
- Make it possible to use variable arguments on ``p*`` commands (``pserve``,
``pshell``, ``pviews``, etc) in the form ``a=1 b=2`` so you can fill in
values in parameterized ``.ini`` file, e.g. ``pshell etc/development.ini
http_port=8080``. See https://github.com/Pylons/pyramid/pull/714
- A somewhat advanced and obscure feature of Pyramid event handlers is their
ability to handle "multi-interface" notifications. These notifications have
traditionally presented multiple objects to the subscriber callable. For
instance, if an event was sent by code like this::
registry.notify(event, context)
In the past, in order to catch such an event, you were obligated to write and
register an event subscriber that mentioned both the event and the context in
its argument list::
@subscriber([SomeEvent, SomeContextType])
def asubscriber(event, context):
pass
In many subscriber callables registered this way, it was common for the logic
in the subscriber callable to completely ignore the second and following
arguments (e.g. ``context`` in the above example might be ignored), because
they usually existed as attributes of the event anyway. You could usually
get the same value by doing ``event.context`` or similar.
The fact that you needed to put an extra argument which you usually ignored
in the subscriber callable body was only a minor annoyance until we added
"subscriber predicates", used to narrow the set of circumstances under which
a subscriber will be executed, in a prior 1.4 alpha release. Once those were
added, the annoyance was escalated, because subscriber predicates needed to
accept the same argument list and arity as the subscriber callables that they
were configured against. So, for example, if you had these two subscriber
registrations in your code::
@subscriber([SomeEvent, SomeContextType])
def asubscriber(event, context):
pass
@subscriber(SomeOtherEvent)
def asubscriber(event):
pass
And you wanted to use a subscriber predicate::
@subscriber([SomeEvent, SomeContextType], mypredicate=True)
def asubscriber1(event, context):
pass
@subscriber(SomeOtherEvent, mypredicate=True)
def asubscriber2(event):
pass
If an existing ``mypredicate`` subscriber predicate had been written in such
a way that it accepted only one argument in its ``__call__``, you could not
use it against a subscription which named more than one interface in its
subscriber interface list. Similarly, if you had written a subscriber
predicate that accepted two arguments, you couldn't use it against a
registration that named only a single interface type.
For example, if you created this predicate::
class MyPredicate(object):
# portions elided...
def __call__(self, event):
return self.val == event.context.foo
It would not work against a multi-interface-registered subscription, so in
the above example, when you attempted to use it against ``asubscriber1``, it
would fail at runtime with a TypeError, claiming something was attempting to
call it with too many arguments.
To hack around this limitation, you were obligated to design the
``mypredicate`` predicate to expect to receive in its ``__call__`` either a
single ``event`` argument (a SomeOtherEvent object) *or* a pair of arguments
(a SomeEvent object and a SomeContextType object), presumably by doing
something like this::
class MyPredicate(object):
# portions elided...
def __call__(self, event, context=None):
return self.val == event.context.foo
This was confusing and bad.
In order to allow people to ignore unused arguments to subscriber callables
and to normalize the relationship between event subscribers and subscriber
predicates, we now allow both subscribers and subscriber predicates to accept
only a single ``event`` argument even if they've been subscribed for
notifications that involve multiple interfaces. Subscribers and subscriber
predicates that accept only one argument will receive the first object passed
to ``notify``; this is typically (but not always) the event object. The
other objects involved in the subscription lookup will be discarded. You can
now write an event subscriber that accepts only ``event`` even if it
subscribes to multiple interfaces::
@subscriber([SomeEvent, SomeContextType])
def asubscriber(event):
# this will work!
This prevents you from needing to match the subscriber callable parameters to
the subscription type unnecessarily, especially when you don't make use of
any argument in your subscribers except for the event object itself.
Note, however, that if the event object is not the first
object in the call to ``notify``, you'll run into trouble. For example, if
notify is called with the context argument first::
registry.notify(context, event)
You won't be able to take advantage of the event-only feature. It will
"work", but the object received by your event handler won't be the event
object, it will be the context object, which won't be very useful::
@subscriber([SomeContextType, SomeEvent])
def asubscriber(event):
# bzzt! you'll be getting the context here as ``event``, and it'll
# be useless
Existing multiple-argument subscribers continue to work without issue, so you
should continue use those if your system notifies using multiple interfaces
and the first interface is not the event interface. For example::
@subscriber([SomeContextType, SomeEvent])
def asubscriber(context, event):
# this will still work!
The event-only feature makes it possible to use a subscriber predicate that
accepts only a request argument within both multiple-interface subscriber
registrations and single-interface subscriber registrations. You needn't
make slightly different variations of predicates depending on the
subscription type arguments. Instead, just write all your subscriber
predicates so they only accept ``event`` in their ``__call__`` and they'll be
useful across all registrations for subscriptions that use an event as their
first argument, even ones which accept more than just ``event``.
However, the same caveat applies to predicates as to subscriber callables: if
you're subscribing to a multi-interface event, and the first interface is not
the event interface, the predicate won't work properly. In such a case,
you'll need to match the predicate ``__call__`` argument ordering and
composition to the ordering of the interfaces. For example, if the
registration for the subscription uses ``[SomeContext, SomeEvent]``, you'll
need to reflect that in the ordering of the parameters of the predicate's
``__call__`` method::
def __call__(self, context, event):
return event.request.path.startswith(self.val)
tl;dr: 1) When using multi-interface subscriptions, always use the event type
as the first subscription registration argument and 2) When 1 is true, use
only ``event`` in your subscriber and subscriber predicate parameter lists,
no matter how many interfaces the subscriber is notified with. This
combination will result in the maximum amount of reusability of subscriber
predicates and the least amount of thought on your part. Drink responsibly.
Bug Fixes
---------
- A failure when trying to locate the attribute ``__text__`` on route and view
predicates existed when the ``debug_routematch`` setting was true or when the
``pviews`` command was used. See https://github.com/Pylons/pyramid/pull/727
Documentation
-------------
- Sync up tutorial source files with the files that are rendered by the
scaffold that each uses.
1.4a4 (2012-11-14)
==================
Features
--------
- ``pyramid.authentication.AuthTktAuthenticationPolicy`` has been updated to
support newer hashing algorithms such as ``sha512``. Existing applications
should consider updating if possible for improved security over the default
md5 hashing.
- Added an ``effective_principals`` route and view predicate.
- Do not allow the userid returned from the ``authenticated_userid`` or the
userid that is one of the list of principals returned by
``effective_principals`` to be either of the strings ``system.Everyone`` or
``system.Authenticated`` when any of the built-in authorization policies that
live in ``pyramid.authentication`` are in use. These two strings are
reserved for internal usage by Pyramid and they will not be accepted as valid
userids.
- Slightly better debug logging from
``pyramid.authentication.RepozeWho1AuthenticationPolicy``.
- ``pyramid.security.view_execution_permitted`` used to return ``True`` if no
view could be found. It now raises a ``TypeError`` exception in that case, as
it doesn't make sense to assert that a nonexistent view is
execution-permitted. See https://github.com/Pylons/pyramid/issues/299.
- Allow a ``_depth`` argument to ``pyramid.view.view_config``, which will
permit limited composition reuse of the decorator by other software that
wants to provide custom decorators that are much like view_config.
- Allow an iterable of decorators to be passed to
``pyramid.config.Configurator.add_view``. This allows views to be wrapped
by more than one decorator without requiring combining the decorators
yourself.
Bug Fixes
---------
- In the past if a renderer returned ``None``, the body of the resulting
response would be set explicitly to the empty string. Instead, now, the body
is left unchanged, which allows the renderer to set a body itself by using
e.g. ``request.response.body = b'foo'``. The body set by the renderer will
be unmolested on the way out. See
https://github.com/Pylons/pyramid/issues/709
- In uncommon cases, the ``pyramid_excview_tween_factory`` might have
inadvertently raised a ``KeyError`` looking for ``request_iface`` as an
attribute of the request. It no longer fails in this case. See
https://github.com/Pylons/pyramid/issues/700
- Be more tolerant of potential error conditions in ``match_param`` and
``physical_path`` predicate implementations; instead of raising an exception,
return False.
- ``pyramid.view.render_view`` was not functioning properly under Python 3.x
due to a byte/unicode discrepancy. See
http://github.com/Pylons/pyramid/issues/721
Deprecations
------------
- ``pyramid.authentication.AuthTktAuthenticationPolicy`` will emit a warning if
an application is using the policy without explicitly passing a ``hashalg``
argument. This is because the default is "md5" which is considered
theoretically subject to collision attacks. If you really want "md5" then you
must specify it explicitly to get rid of the warning.
Documentation
-------------
- All of the tutorials that use
``pyramid.authentication.AuthTktAuthenticationPolicy`` now explicitly pass
``sha512`` as a ``hashalg`` argument.
Internals
---------
- Move ``TopologicalSorter`` from ``pyramid.config.util`` to ``pyramid.util``,
move ``CyclicDependencyError`` from ``pyramid.config.util`` to
``pyramid.exceptions``, rename ``Singleton`` to ``Sentinel`` and move from
``pyramid.config.util`` to ``pyramid.util``; this is in an effort to
move that stuff that may be an API one day out of ``pyramid.config.util``,
because that package should never be imported from non-Pyramid code.
TopologicalSorter is still not an API, but may become one.
- Get rid of shady monkeypatching of ``pyramid.request.Request`` and
``pyramid.response.Response`` done within the ``__init__.py`` of Pyramid.
Webob no longer relies on this being done. Instead, the ResponseClass
attribute of the Pyramid Request class is assigned to the Pyramid response
class; that's enough to satisfy WebOb and behave as it did before with the
monkeypatching.
1.4a3 (2012-10-26)
==================
Bug Fixes
---------
- The match_param predicate's text method was fixed to sort its values.
Part of https://github.com/Pylons/pyramid/pull/705
- 1.4a ``pyramid.scripting.prepare`` behaved differently than 1.3 series
function of same name. In particular, if passed a request, it would not
set the ``registry`` attribute of the request like 1.3 did. A symptom
would be that passing a request to ``pyramid.paster.bootstrap`` (which uses
the function) that did not have a ``registry`` attribute could assume that
the registry would be attached to the request by Pyramid. This assumption
could be made in 1.3, but not in 1.4. The assumption can now be made in
1.4 too (a registry is attached to a request passed to bootstrap or
prepare).
- When registering a view configuration that named a Chameleon ZPT renderer
with a macro name in it (e.g. ``renderer='some/template#somemacro.pt``) as
well as a view configuration without a macro name it it that pointed to the
same template (e.g. ``renderer='some/template.pt'``), internal caching could
confuse the two, and your code might have rendered one instead of the
other.
Features
--------
- Allow multiple values to be specified to the ``request_param`` view/route
predicate as a sequence. Previously only a single string value was allowed.
See https://github.com/Pylons/pyramid/pull/705
- Comments with references to documentation sections placed in scaffold
``.ini`` files.
- Added an HTTP Basic authentication policy
at ``pyramid.authentication.BasicAuthAuthenticationPolicy``.
- The Configurator ``testing_securitypolicy`` method now returns the policy
object it creates.
- The Configurator ``testing_securitypolicy`` method accepts two new
arguments: ``remember_result`` and ``forget_result``. If supplied, these
values influence the result of the policy's ``remember`` and ``forget``
methods, respectively.
- The DummySecurityPolicy created by ``testing_securitypolicy`` now sets a
``forgotten`` value on the policy (the value ``True``) when its ``forget``
method is called.
- The DummySecurityPolicy created by ``testing_securitypolicy`` now sets a
``remembered`` value on the policy, which is the value of the ``principal``
argument it's called with when its ``remember`` method is called.
- New ``physical_path`` view predicate. If specified, this value should be a
string or a tuple representing the physical traversal path of the context
found via traversal for this predicate to match as true. For example:
``physical_path='/'`` or ``physical_path='/a/b/c'`` or ``physical_path=('',
'a', 'b', 'c')``. This is not a path prefix match or a regex, it's a
whole-path match. It's useful when you want to always potentially show a
view when some object is traversed to, but you can't be sure about what kind
of object it will be, so you can't use the ``context`` predicate. The
individual path elements inbetween slash characters or in tuple elements
should be the Unicode representation of the name of the resource and should
not be encoded in any way.
1.4a2 (2012-09-27)
==================
Bug Fixes
---------
- When trying to determine Mako defnames and Chameleon macro names in asset
specifications, take into account that the filename may have a hyphen in
it. See https://github.com/Pylons/pyramid/pull/692
Features
--------
- A new ``pyramid.session.check_csrf_token`` convenience function was added.
- A ``check_csrf`` view predicate was added. For example, you can now do
``config.add_view(someview, check_csrf=True)``. When the predicate is
checked, if the ``csrf_token`` value in ``request.params`` matches the CSRF
token in the request's session, the view will be permitted to execute.
Otherwise, it will not be permitted to execute.
- Add ``Base.metadata.bind = engine`` to alchemy template, so that tables
defined imperatively will work.
Documentation
-------------
- update wiki2 SQLA tutorial with the changes required after inserting
``Base.metadata.bind = engine`` into the alchemy scaffold.
1.4a1 (2012-09-16)
==================
Bug Fixes
---------
- Forward port from 1.3 branch: When no authentication policy was configured,
a call to ``pyramid.security.effective_principals`` would unconditionally
return the empty list. This was incorrect, it should have unconditionally
returned ``[Everyone]``, and now does.
- Explicit url dispatch regexes can now contain colons.
https://github.com/Pylons/pyramid/issues/629
- On at least one 64-bit Ubuntu system under Python 3.2, using the
``view_config`` decorator caused a ``RuntimeError: dictionary changed size
during iteration`` exception. It no longer does. See
https://github.com/Pylons/pyramid/issues/635 for more information.
- In Mako Templates lookup, check if the uri is already adjusted and bring
it back to an asset spec. Normally occurs with inherited templates or
included components.
https://github.com/Pylons/pyramid/issues/606
https://github.com/Pylons/pyramid/issues/607
- In Mako Templates lookup, check for absolute uri (using mako directories)
when mixing up inheritance with asset specs.
https://github.com/Pylons/pyramid/issues/662
- HTTP Accept headers were not being normalized causing potentially
conflicting view registrations to go unnoticed. Two views that only
differ in the case ('text/html' vs. 'text/HTML') will now raise an error.
https://github.com/Pylons/pyramid/pull/620
- Forward-port from 1.3 branch: when registering multiple views with an
``accept`` predicate in a Pyramid application runing under Python 3, you
might have received a ``TypeError: unorderable types: function() <
function()`` exception.
Features
--------
- Configurator.add_directive now accepts arbitrary callables like partials or
objects implementing ``__call__`` which dont have ``__name__`` and
``__doc__`` attributes. See https://github.com/Pylons/pyramid/issues/621
and https://github.com/Pylons/pyramid/pull/647.
- Third-party custom view, route, and subscriber predicates can now be added
for use by view authors via
``pyramid.config.Configurator.add_view_predicate``,
``pyramid.config.Configurator.add_route_predicate`` and
``pyramid.config.Configurator.add_subscriber_predicate``. So, for example,
doing this::
config.add_view_predicate('abc', my.package.ABCPredicate)
Might allow a view author to do this in an application that configured that
predicate::
@view_config(abc=1)
Similar features exist for ``add_route``, and ``add_subscriber``. See
"Adding A Third Party View, Route, or Subscriber Predicate" in the Hooks
chapter for more information.
Note that changes made to support the above feature now means that only
actions registered using the same "order" can conflict with one another.
It used to be the case that actions registered at different orders could
potentially conflict, but to my knowledge nothing ever depended on this
behavior (it was a bit silly).
- Custom objects can be made easily JSON-serializable in Pyramid by defining
a ``__json__`` method on the object's class. This method should return
values natively serializable by ``json.dumps`` (such as ints, lists,
dictionaries, strings, and so forth).
- The JSON renderer now allows for the definition of custom type adapters to
convert unknown objects to JSON serializations.
- As of this release, the ``request_method`` predicate, when used, will also
imply that ``HEAD`` is implied when you use ``GET``. For example, using
``@view_config(request_method='GET')`` is equivalent to using
``@view_config(request_method=('GET', 'HEAD'))``. Using
``@view_config(request_method=('GET', 'POST')`` is equivalent to using
``@view_config(request_method=('GET', 'HEAD', 'POST')``. This is because
HEAD is a variant of GET that omits the body, and WebOb has special support
to return an empty body when a HEAD is used.
- ``config.add_request_method`` has been introduced to support extending
request objects with arbitrary callables. This method expands on the
previous ``config.set_request_property`` by supporting methods as well as
properties. This method now causes less code to be executed at
request construction time than ``config.set_request_property`` in
version 1.3.
- Don't add a ``?`` to URLs generated by ``request.resource_url`` if the
``query`` argument is provided but empty.
- Don't add a ``?`` to URLs generated by ``request.route_url`` if the
``_query`` argument is provided but empty.
- The static view machinery now raises (rather than returns) ``HTTPNotFound``
and ``HTTPMovedPermanently`` exceptions, so these can be caught by the
NotFound view (and other exception views).
- The Mako renderer now supports a def name in an asset spec. When the def
name is present in the asset spec, the system will render the template def
within the template and will return the result. An example asset spec is
``package:path/to/template#defname.mako``. This will render the def named
``defname`` inside the ``template.mako`` template instead of rendering the
entire template. The old way of returning a tuple in the form
``('defname', {})`` from the view is supported for backward compatibility,
- The Chameleon ZPT renderer now accepts a macro name in an asset spec. When
the macro name is present in the asset spec, the system will render the
macro listed as a ``define-macro`` and return the result instead of
rendering the entire template. An example asset spec:
``package:path/to/template#macroname.pt``. This will render the macro
defined as ``macroname`` within the ``template.pt`` template instead of the
entire templae.
- When there is a predicate mismatch exception (seen when no view matches for
a given request due to predicates not working), the exception now contains
a textual description of the predicate which didn't match.
- An ``add_permission`` directive method was added to the Configurator. This
directive registers a free-standing permission introspectable into the
Pyramid introspection system. Frameworks built atop Pyramid can thus use
the the ``permissions`` introspectable category data to build a
comprehensive list of permissions supported by a running system. Before
this method was added, permissions were already registered in this
introspectable category as a side effect of naming them in an ``add_view``
call, this method just makes it possible to arrange for a permission to be
put into the ``permissions`` introspectable category without naming it
along with an associated view. Here's an example of usage of
``add_permission``::
config = Configurator()
config.add_permission('view')
- The ``UnencryptedCookieSessionFactoryConfig`` now accepts
``signed_serialize`` and ``signed_deserialize`` hooks which may be used
to influence how the sessions are marshalled (by default this is done
with HMAC+pickle).
- ``pyramid.testing.DummyRequest`` now supports methods supplied by the
``pyramid.util.InstancePropertyMixin`` class such as ``set_property``.
- Request properties and methods added via ``config.set_request_property`` or
``config.add_request_method`` are now available to tweens.
- Request properties and methods added via ``config.set_request_property`` or
``config.add_request_method`` are now available in the request object
returned from ``pyramid.paster.bootstrap``.
- ``request.context`` of environment request during ``bootstrap`` is now the
root object if a context isn't already set on a provided request.
- The ``pyramid.decorator.reify`` function is now an API, and was added to
the API documentation.
- Added the ``pyramid.testing.testConfig`` context manager, which can be used
to generate a configurator in a test, e.g. ``with testing.testConfig(...):``.
- Users can now invoke a subrequest from within view code using a new
``request.invoke_subrequest`` API.
Deprecations
------------
- The ``pyramid.config.Configurator.set_request_property`` has been
documentation-deprecated. The method remains usable but the more
featureful ``pyramid.config.Configurator.add_request_method`` should be
used in its place (it has all of the same capabilities but can also extend
the request object with methods).
Backwards Incompatibilities
---------------------------
- The Pyramid router no longer adds the values ``bfg.routes.route`` or
``bfg.routes.matchdict`` to the request's WSGI environment dictionary.
These values were docs-deprecated in ``repoze.bfg`` 1.0 (effectively seven
minor releases ago). If your code depended on these values, use
request.matched_route and request.matchdict instead.
- It is no longer possible to pass an environ dictionary directly to
``pyramid.traversal.ResourceTreeTraverser.__call__`` (aka
``ModelGraphTraverser.__call__``). Instead, you must pass a request
object. Passing an environment instead of a request has generated a
deprecation warning since Pyramid 1.1.
- Pyramid will no longer work properly if you use the
``webob.request.LegacyRequest`` as a request factory. Instances of the
LegacyRequest class have a ``request.path_info`` which return a string.
This Pyramid release assumes that ``request.path_info`` will
unconditionally be Unicode.
- The functions from ``pyramid.chameleon_zpt`` and ``pyramid.chameleon_text``
named ``get_renderer``, ``get_template``, ``render_template``, and
``render_template_to_response`` have been removed. These have issued a
deprecation warning upon import since Pyramid 1.0. Use
``pyramid.renderers.get_renderer()``,
``pyramid.renderers.get_renderer().implementation()``,
``pyramid.renderers.render()`` or ``pyramid.renderers.render_to_response``
respectively instead of these functions.
- The ``pyramid.configuration`` module was removed. It had been deprecated
since Pyramid 1.0 and printed a deprecation warning upon its use. Use
``pyramid.config`` instead.
- The ``pyramid.paster.PyramidTemplate`` API was removed. It had been
deprecated since Pyramid 1.1 and issued a warning on import. If your code
depended on this, adjust your code to import
``pyramid.scaffolds.PyramidTemplate`` instead.
- The ``pyramid.settings.get_settings()`` API was removed. It had been
printing a deprecation warning since Pyramid 1.0. If your code depended on
this API, use ``pyramid.threadlocal.get_current_registry().settings``
instead or use the ``settings`` attribute of the registry available from
the request (``request.registry.settings``).
- These APIs from the ``pyramid.testing`` module were removed. They have
been printing deprecation warnings since Pyramid 1.0:
* ``registerDummySecurityPolicy``, use
``pyramid.config.Configurator.testing_securitypolicy`` instead.
* ``registerResources`` (aka ``registerModels``, use
``pyramid.config.Configurator.testing_resources`` instead.
* ``registerEventListener``, use
``pyramid.config.Configurator.testing_add_subscriber`` instead.
* ``registerTemplateRenderer`` (aka `registerDummyRenderer``), use
``pyramid.config.Configurator.testing_add_template`` instead.
* ``registerView``, use ``pyramid.config.Configurator.add_view`` instead.
* ``registerUtility``, use
``pyramid.config.Configurator.registry.registerUtility`` instead.
* ``registerAdapter``, use
``pyramid.config.Configurator.registry.registerAdapter`` instead.
* ``registerSubscriber``, use
``pyramid.config.Configurator.add_subscriber`` instead.
* ``registerRoute``, use
``pyramid.config.Configurator.add_route`` instead.
* ``registerSettings``, use
``pyramid.config.Configurator.add_settings`` instead.
- In Pyramid 1.3 and previous, the ``__call__`` method of a Response object
was invoked before any finished callbacks were executed. As of this
release, the ``__call__`` method of a Response object is invoked *after*
finished callbacks are executed. This is in support of the
``request.invoke_subrequest`` feature.
Documentation
-------------
- Added an "Upgrading Pyramid" chapter to the narrative documentation. It
describes how to cope with deprecations and removals of Pyramid APIs and
how to show Pyramid-generated deprecation warnings while running tests and
while running a server.
- Added a "Invoking a Subrequest" chapter to the documentation. It describes
how to use the new ``request.invoke_subrequest`` API.
Dependencies
------------
- Pyramid now requires WebOb 1.2b3+ (the prior Pyramid release only relied on
1.2dev+). This is to ensure that we obtain a version of WebOb that returns
``request.path_info`` as text.